Several mice, used in research experiments in June 2015 at the University of Minnesota, were supposed to have been euthanized. Instead, lab staff later found them alive in a carcass cooler.

Two months later, an unknown number of mice underwent surgery inside U research facilities. None received pre- or post-op anesthesia.

Seventy-five rats in April 2016 underwent a surgical procedure at a university lab, without receiving any type of post-op pain medication. In another incident, experimenters drew blood from behind mice’s eyes, but failed to provide pain relief to the animals.

These are four of 60 animal-welfare violations the University of Minnesota racked up over an 18-month period from January 2015 to April 1, 2017, according to a study released by PETA yesterday.

The nonprofit's findings showed that universities often shirk or cut corners when it comes to the humane care of mice and rats. And in the case of these species in particular, the study revealed there is no bigger violator than the University of Minnesota.

PETA researchers scrutinized federal reports obtained through FOIA requests, documenting animal-welfare violations at the top 20 university recipients of National Institutes of Health grants. These institutions, which include the U, University of Pittsburgh, and Yale, received more than $6 billion in NIH grants in 2016.

But that money comes with an understanding. The schools will comply with federal animal welfare guidelines in their treatment of rats and mice, which make up 95 percent of those used in American research labs, but have no official protection under federal law.

Of the 20 universities, Minnesota's 60 violations were by far the most, seven more than second place offender, the University of Pittsburgh.

University of Minnesota spokesperson Dan Gilchrist responded to PETA's study in a statement. "When problems are reported, either as part of regular inspections by the U of M or federal regulators, or by investigators themselves, the involved researchers are required to provide responses to all findings and concerns to outline how they will address these issues in the future. To be clear, the reports in question have all been reported previously to University officials and addressed with researchers."

"These guidelines and regulations represent a minimal standard of care. The fact that these institutions, and the University of Minnesota in particular, continue to violate them shows that they could care less," she says. "It was really disappointing for us to see how many violations [there were] at the University of Minnesota. The average overall was 21 violations. So when you look at the difference, that's obviously significant."

According to the U's most current annual animal report filed with the U.S. Department of Agriculture, in addition to rats and mice, the school's research facilities had about 2,000 animals under its care in 2015. That number includes 70 dogs, 96 non-human primates, and more than 300 pigs.